A throttle control method includes generating a throttle request based on a drag torque request and setting a throttle command equal to the throttle request when the throttle request is less than a throttle idle maximum. A throttle maximum increase is determined when the throttle request is greater than the throttle idle maximum and the throttle command is determined based on the throttle maximum increase. The throttle is controlled based on the throttle command.
|
18. A method of controlling a throttle, comprising:
generating a throttle request based on a drag torque request;
setting a throttle command equal to said throttle request when said throttle request is less than a throttle idle maximum;
determining a throttle maximum increase when said throttle request is greater than said throttle idle maximum;
determining said throttle command based on said throttle maximum increase; and
controlling said throttle based on said throttle command.
11. A drag torque control system for a vehicle engine, comprising:
a throttle that regulates torque output of said engine;
a control module that generates a throttle control signal based on a drag torque request, that sets said throttle control signal equal to a throttle request when said throttle request is less than a throttle idle maximum, determines a throttle maximum increase when said throttle request is greater than said throttle idle maximum, determines said throttle control signal based on said throttle maximum increase and controls said throttle based on said throttle control signal.
1. A drag torque control system for a vehicle engine, comprising:
a throttle that regulates a torque output of said engine;
a control module that saves first and second drag torque requests in first and second memories, respectively, said second drag torque request being equal to said first drag torque request, which is determined based on vehicle operating parameters, wherein said control module compares said first and second drag torque requests to one another to monitor for corrupted memory values and generates a throttle control signal based on one of said first and second drag torque requests when said first and second drag torque requests match, wherein said throttle is regulated based on said throttle control signal to achieve said one of said first and second drag torque requests.
26. A method of providing secure drag torque control in a vehicle engine, comprising:
generating a drag torque request;
storing said drag torque request and a corresponding timestamp in a first memory of a first control module;
storing said drag torque request and said corresponding timestamp in a second memory of a second control module;
reading a previous drag torque request and corresponding timestamp from said second memory of said second control module;
receiving said previous drag torque request and corresponding timestamp at said first control module;
comparing said previous drag torque request and said corresponding timestamp to drag torque requests and corresponding timestamps stored in said first memory to monitor for corrupted memory values; and
initiating drag torque control based on said previous drag torque request when said previous drag torque request and said corresponding timestamp of said second memory and one of said drag torque requests and corresponding timestamps of said first memory are equivalent.
2. The drag torque control system of
3. The drag torque control system of
4. The drag torque control system of
5. The drag torque control system of
6. The drag torque control system of
7. The drag torque control system of
8. The drag torque control system of
9. The drag torque control system of
10. The drag torque control system of
12. The drag torque control system of
13. The drag torque control system of
14. The drag torque control system of
15. The drag torque control system of
16. The drag torque control system of
17. The drag torque control system of
20. The method of
storing said drag torque request in first and second memories;
comparing said drag torque request from said first and second memories to one another after generating said throttle request; and
limiting said throttle command to said throttle idle maximum if said drag torque request stored in said first memory is not equivalent to said drag torque request stored in said second memory.
21. The method of
comparing a wheel slip to a wheel slip threshold; and
limiting said throttle command to said throttle idle maximum when said wheel slip is less than said wheel slip threshold.
22. The method of
23. The method of
24. The method of
25. The method of
27. The method of
28. The method of
29. The method of
generating a throttle request based on said drag torque request;
setting a throttle command equal to said throttle request when said throttle request is less than a throttle idle maximum;
determining a throttle maximum increase when said throttle request is greater than said throttle idle maximum;
determining said throttle command based on said throttle maximum increase; and
controlling said throttle based on said throttle command.
31. The method of
again storing said drag torque request in first and second memories;
again comparing said drag torque request from said first and second memories to one another after generating said throttle request; and
limiting said throttle command to said throttle idle maximum if said drag torque request stored in said first memory is not equivalent to said drag torque request stored in said second memory.
32. The method of
comparing a wheel slip to a wheel slip threshold; and
limiting said throttle command to said throttle idle maximum when said wheel slip is less than said wheel slip threshold.
33. The method of
34. The method of
35. The method of
36. The method of
|
The present invention relates to electronic throttle control (ETC), and more particularly to drag torque request security for an ETC system.
Wheel slip can occur as a result of engine drag or braking on the driven wheels of a vehicle. More particularly, when a driver suddenly releases the throttle, the engine drag force can become larger than the frictional force between the road and the driven wheels. As a result, the driven wheels slip or skid on the road surface. Vehicle stability can be reduced, especially in the case of a rear-wheel drive vehicle traveling on a low-coefficient of friction surface, such as wet pavement, gravel, ice or snow covered roads and the like.
Vehicle stability systems sometimes include an engine drag control (EDC) module that reduces wheel slip during closed throttle, non-braking deceleration. In general, the EDC module generates a drag torque request that indicates an increase in engine torque that is required to reduce wheel slip and improve vehicle stability. The EDC module can be implemented by an anti-lock braking system (ABS) module and an engine control module (ECM) or other modules and controllers. The ABS module determines the drag torque request and transmits it to the ECM module. The module ECM regulates the engine based on the drag torque request. The drag torque request and resultant throttle control is generated by the EDC module and is not operator generated. Therefore, the drag torque request should be secure and the resultant throttle control not startling to the operator. In other words, the drag torque request should not produce an unsafe driving condition or produce a sudden, high engine torque output that is startling to the operator.
Accordingly, the present invention provides a method of controlling a throttle. The method includes generating a throttle request based on a drag torque request and setting a throttle command equal to the throttle request when the throttle request is less than a throttle idle maximum. A throttle maximum increase is determined when the throttle request is greater than the throttle idle maximum and the throttle command is determined based on the throttle maximum increase. The throttle is controlled based on the throttle command.
In one feature, the method further includes limiting the throttle request to a throttle maximum.
In another feature, the method further includes storing the drag torque request in first and second memories and comparing the drag torque request from the first and second memories after generating the throttle request. The throttle command is limited to the throttle idle maximum if the drag torque request stored in the first memory does not correspond to the drag torque request stored in the second memory.
In another feature, the method further includes comparing a wheel slip to a wheel slip threshold and limiting the throttle command to the throttle idle maximum when the wheel slip is less than the wheel slip threshold.
In still another feature, the throttle maximum increase is determined based on engine speed and vehicle speed. The throttle maximum increase is determined from a look-up table.
In yet another feature, the throttle command is determined based on the throttle request, the throttle idle maximum, a previous throttle command and the throttle maximum increase. The throttle command is a minimum between the throttle request and a maximum of the throttle idle maximum and a sum of the previous throttle command and the throttle maximum increase.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, or other suitable components that provide the described functionality.
Referring now to
A controller 24 controls overall operation of the vehicle 10 based on vehicle operating parameters and an operator input 26. While a single controller 24 is shown, one or more controllers may be implemented. The operator input 26 can include an accelerator pedal, a brake pedal, cruise control and the like. Generally, the operator input indicates the desired amount of throttling of the engine system 12. A throttle position sensor 28 generates a throttle position signal that is communicated to the controller 24. The controller 24 generates a throttle control signal that is sent to a throttle actuator 30, which regulates the throttle position. An engine speed sensor 32 generates an engine speed signal (RPM) that is communicated to the controller 24. Wheel speed sensors 34 generate wheel speed signals (RPM) that are communicated to the controller 24. The controller 24 calculates vehicle speed based on the wheel speed signals. Additionally, the controller 24 calculates wheel slip as the difference between the wheel speed of the driven wheels 14 and the wheel speed of the non-driven wheels 16.
Referring now to
Referring now to
In step 214, control determines whether the timestamp value corresponding to TDRAGREQ matches the value stored in the FIFO array. If the FIFO array does not include the corresponding timestamp, control continues in step 216. If the FIFO array includes the corresponding timestamp, control continues in step 218. In step 216, control increments the counter by one. Control compares the counter to a counter threshold in step 220. If the counter is less than the counter threshold, control continues in step 222. If the counter is greater than or equal to the counter threshold, control exits drag control in step 224, signals a fault in step 226 and control ends. In this manner, drag control is terminated to avoid improper engine operation based on a corrupted memory value.
Control determines whether TDRAGREQ matches that stored in the FIFO array in step 218. If none of the FIFO array values match TDRAGREQ, the memory is deemed faulty and control continues in step 224. If the FIFO array values include TDRAGREQ, control continues in step 222. In step 222, control determines whether drag control is active. If drag control is not active, control ends. If drag control is active, control continues in step 228. In step 228, control controls the throttle based on TDRAGREQ, as described in further detail below. Once a TDRAGREQ/timestamp match is found in the FIFO array, that pair is no longer used for future control iterations (i.e., the pair falls out of the FIFO array).
The ETC memory check control provides a handshaking method in the case where multiple modules execute the ETC drag control of the present invention. For example, in the case where the ABS module generates TDRAGREQ and the ECM controls the throttle based on TDRAGREQ, the ETC memory check ensures accurate communication between the modules. Additionally, the ETC memory check monitors for corrupted memory values. More particularly, the ECM controls the throttle based on TDRAGREQ using the same memory variable communicated from the ABS module. In this manner, if the memory value becomes corrupted where the ECM processes it, the same corrupted value is again received by the ABS module.
Referring now to
In step 300, control sets a timer and a counter equal to zero. In step 302, control receives and stores TDRAGREQ in dual memory stores. The memory stores are preferably provided as RAM variables. It is anticipated that the first RAM variable stores TDRAGREQ and the second RAM variable stores the two's complement of TDRAGREQ. In step 304, control calculates a throttle area (ADRAG) based on TDRAGREQ.
In step 306, control determines whether the stored values are equal. In the case of the first RAM variable storing TDRAGREQ and the second RAM variable storing the two's complement, the sum of the dual stores should equal zero. If the dual store values are not equal, control continues in step 308. If the dual store values are equal, control continues in step 310. In step 308, control increments the counter by one. Control determines whether the counter is less than a counter threshold in step 312. If the counter is less than the counter threshold, control continues sets a drag throttle area command (ADRAGCOM) to a maximum idle throttle area (AIDLEMAX) in step 314. AIDLEMAX is a pre-selected throttle area such that instantaneous requests for a throttle area at or below this value will not cause discomforting vehicle acceleration. In this manner, control limits ADRAGCOM to AIDLEMAX when the dual stores are consistently unequal and an error flag is enabled indicated a fault (e.g., memory value corruption). Control continues in step 316, as described in further detail below. If the counter is greater than or equal to the counter threshold, control enables an error flag in step 313, exits drag control in step 315 and control ends.
Control determines whether ADRAG is greater than a maximum drag throttle area (ADRAGMAX) in step 310. If ADRAG is less than ADRAGMAX, control continues in step 318. If ADRAG is greater than ADRAGMAX, control sets ADRAG equal to ADRAGMAX in step 320 and continues in step 318. In this manner, ADRAG is limited by ADRAGMAX. In step 318, control determines whether ADRAG is greater than AIDLEMAX. If ADRAG is not greater than AIDLEMAX, control continues in step 322. If ADRAG is greater than AIDLEMAX, control continues in step 324. In step 322, control sets ADRAGCOM equal to ADRAG. Control resets the timer to zero in step 326 and continues in step 316.
Control increments the timer by one in step 324. In step 328, control determines a maximum drag throttle area increase (ADRAGMAXINC). ADRAGMAXINC is the maximum amount of throttle area increase allowed for drag control. ADRAGMAXINC is determined from a look-up table based on engine speed (RPM) and vehicle speed. In step 330, control determines ADRAGCOM based on ADRAG, AIDLEMAX, the previous drag command (ADRAGCOMPREV) and ADRAGMAXINC. ADRAGCOM is determined according to the following:
ADRAGCOM=min(ADRAG, max(AIDLEMAX,(ADRAGCOMPREV+ADRAGMAXINC)))
In step 332, control determines whether the wheel slip is less than a threshold. The wheel slip threshold indicates the point at which the wheel slip has become so low that wheel slip is on the verge of ceasing (i.e., driven wheel speed is almost equal to non-driven wheel speed). If the wheel slip is less than the threshold, control continues in step 334. If the wheel slip is not less than the threshold, control continues in step 316. In step 334, control sets ADRAGCOM equal to AIDLEMAX and ADRAG equal to AIDLEMAX and control continues in step 316.
In step 316, control sets ADRAGCOMPREV equal to ADRAGCOM. In this manner, ADRAGCOMPREV is updated for use in step 330 in the next loop of the ETC drag torque request security control. In step 336, control determines whether the timer is less than a threshold. The threshold can be within the range of 100 ms-400 ms. If the timer is not less than the threshold, control ends. If the timer is less than the threshold, ADRAGCOM is set equal to ADRAG in step 338 and control ends. The timer monitors how often ADRAG is greater than AIDLEMAX. If ADRAG is greater than AIDLEMAX for less than the threshold time, ADRAGCOM is set equal to ADRAG. In this manner, ADRAG is not rate limited until the threshold expires.
The ETC drag torque rate limiting control limits the rate of drag torque to improve operating comfort. Further, the ETC drag torque rate limiting control improves ETC security during periods of drag control. More particularly, the ETC drag torque rate limiting control limits drag requests up to a maximum calibration greater than AIDLEMAX. That is to say, ADRAGCOM is rate limited when above AIDLEMAX. Further, full drag authority is enabled for a period of time when first transitioning above AIDLEMAX. In this manner, the intake manifold is filled faster. However, after continuous requests above AIDLEMAX, ADRAGCOM is rate limited. If driven wheel speed comes close to or exceeds the non-driven wheel speed at any time during the drag event, ADRAGCOM is set to AIDLEMAX. In this manner, the wheel speed feedback provides an inferred drag check.
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.
Squire, Matthew, Bauerle, Paul A., Katrak, Kerfegar K., Roberts, Colin A.
Patent | Priority | Assignee | Title |
7861688, | Jan 30 2006 | Toyota Jidosha Kabushiki Kaisha | Control apparatus and method of an internal combustion engine |
8396680, | Oct 20 2008 | GM Global Technology Operations LLC | System and method for identifying issues in current and voltage measurements |
8793002, | Jun 20 2008 | Caterpillar Inc. | Torque load control system and method |
Patent | Priority | Assignee | Title |
5692472, | Sep 28 1995 | Robert Bosch GmbH | Method and arrangement for controlling the drive unit of a motor vehicle |
6240355, | Oct 28 1998 | Robert Bosch GmbH | Method and device for controlling the drag torque of an internal combustion engine |
6285946, | Nov 03 1997 | Robert Bosch GmbH | Method and device for controlling a drive unit of a vehicle |
6287237, | Apr 13 1999 | Continental Automotive GmbH | Method of controlling the drive train of a motor vehicle and drive train controller of a motor vehicle |
6535809, | Nov 08 2000 | BWI COMPANY LIMITED S A | Vehicle engine torque control with engine drag control mode |
20030018426, |
Date | Maintenance Fee Events |
May 11 2011 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
May 27 2015 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Jul 29 2019 | REM: Maintenance Fee Reminder Mailed. |
Jan 13 2020 | EXP: Patent Expired for Failure to Pay Maintenance Fees. |
Date | Maintenance Schedule |
Dec 11 2010 | 4 years fee payment window open |
Jun 11 2011 | 6 months grace period start (w surcharge) |
Dec 11 2011 | patent expiry (for year 4) |
Dec 11 2013 | 2 years to revive unintentionally abandoned end. (for year 4) |
Dec 11 2014 | 8 years fee payment window open |
Jun 11 2015 | 6 months grace period start (w surcharge) |
Dec 11 2015 | patent expiry (for year 8) |
Dec 11 2017 | 2 years to revive unintentionally abandoned end. (for year 8) |
Dec 11 2018 | 12 years fee payment window open |
Jun 11 2019 | 6 months grace period start (w surcharge) |
Dec 11 2019 | patent expiry (for year 12) |
Dec 11 2021 | 2 years to revive unintentionally abandoned end. (for year 12) |